[Griefbringer]

In an advance/delay battle, the advancing side can use up to 30 % of points in artillery before overload points start being awarded, while the defending side can spend up to 15 %. Furthermore, the attacking side gets 50% more points overall than the defender.

So if the defending force was 4000 points, this would give an attacking force of 6000 points, and the artillery overload limits would be 600 and 1800 points, respectively.